The experiments described in the preset proposal are designed to determine the mechanism for the initiation of feeding using a simple system, the mollusc Aplysia californica. Both preabsorptive (e.g., relief of gut stretch) and postabsorptive (e.g., blood glucose) factors will be investigated as initiating stimuli. Once the initiating stimuli are understood electrophysiological techniques will be employed to investigate the neuronal sites of action of the signals related to the initiating stimuli, using semi-intact and in vivo preparations. In addition, anatomical techniques of tract tracing and neural staining will be used to determine possible routes of transmission of these stimuli. It is the intention that general principles derived from understanding the physiology of the initiation of feeding in this simple system can be applied to vertebrate systems of feeding behavior, both in healthy and diseased states.